The Commissioner wrote to every member of the force as both the Garda Representative Authority (GRA) and Association of Garda Sergeants and Inspectors (AGSI) rejected pay deals from Government.

Tanaiste Justice Minister Frances Fitzgerald said she hoped the threatened repeat of the 1998 blue flu, when gardai called in sick en masse, will not materialise.

And she warned that officers who do not turn in will not be paid and could face sanctions.

"Breaches of discipline can arise if people fail to obey the directive from the Garda Commissioner," she said.

In a stark warning to about 12,500 officers Commissioner O'Sullivan gave them 24 hours to confirm they will show up for work on Friday and the subsequent three Fridays this month when strikes are planned.

She said the prospect of a policing crisis with only the top brass and armed response units on duty was unprecedented.

"In particular, the action proposed for Friday 4th November and subsequently is without precedent and is gravely damaging for the delivery of a policing and security service for this country as well as for An Garda Siochana as an organisation and each individual member," she said.

Garda management in each district will be asked to direct officers to their duties on each day of the threatened strike.

The letter ratchets up an already deeply divisive dispute over pay restoration and equal rates for newly graduated officers.

The offer of a revival of the 4,000 euro rent allowance and a fee to cover the 15-minute shift changeover for gardai was rejected by the garda representative bodies but contacts with government were ongoing in the hope that the Labour Court could be asked to adjudicate.

Gardai are barred from striking under law.

But the Commissioner's letter contained no indications about possible sanctions for officers who do not meet her demands for the 24 hours from 7am on Friday.

The Garda chief said: "An Garda Siochana has a long-established and proud tradition of placing our communities at the heart of everything we do.

"In order to maintain this position it is obligatory that we ensure public safety and protection by providing a guaranteed policing service and maintaining the security of the state at all times.

"I am confident of your support in these difficult circumstances and I remain confident that the professionalism, dedication and commitment of the members of An Garda Siochana will prevail in the face of these challenges."

The Tanaiste and Minister for Public Expenditure and Reform Paschal Donohoe urged the garda representatives to meet them, but warned that any deal would have to be agreed with the limits of the public sector pay plans set out in the Lansdowne Road Agreement.

Discussions are also continuing on contingency policing plans in the event that large numbers of officers do not show up for work on Friday.